$2 CPM for video ads is really not that unusual.

True they are video ads. That's a good point. Still, twitch won't share all of it.

Yeah that's a very good point, I couldn't find any reliable source on twitch's website. I had to dig in many /r/twitch comments to find the cpm and hoped that they were telling the truth. In any case, I am pretty sure that my numbers are really a lower bound for how much money the streamers make. Most streamers receive more donations then subscribers, and donations don't have a fixed cost.

Yup, all streamers earn a lot more money from subscribers than ads. You can see that in their streams. They pay more attention to subs and most hardly ever run ads.

The estimated ad rate is way too high.

This is actually a good point, many of the higher viewer streams I see don't use ads all that much and many of the "full time streamers" really seem to value subscribers yet I imagine a strong reason for this is that a subscriber has a good chance at also being a donator. I Imagine twitch also uses subscriber numbers as a sort of measure as to who gets featured more often and such.

"We considered that only 24% of the viewers get to see the ads put up by the streamer according to a poll."

I don't know, I feel like that number just seems way too high.

after spending a decent amount of time watching these streamers and participating in the league of legends community, it seems that actually a fair amount of viewers turn off ad-block while watching their favorite streamer. I do it for example, if it means that Pobelter http://www.twitch.tv/pobelter is gonna earn a bit more money.

$2 is pretty good for rev share. Much of those impressions are clearing at $20+